Relay control device



Jan. 10, 1933.

c. 1. HALL 1,894,095

RELAY CONTROL DEVICE Filed Aug. 18, 1930 Inventor: Chester- 1. Ha", by/wMi M His Attorneg.

Patented Jan. 10, 1933 UNITED STATES PATENT OFFICE CHESTER I. HALL, OFPHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO GENERAL ELECTRIC COMPANY, ACORPORATION OF NEW YORK RELAY CONTROL DEVICE Application filed August18, 1930. Serial No. 475,973.

My invention relates to-relay control devices, more particularly to anelectromagnetic relay control for use with alternating current circuits.

In the usual forms of relay control such for example as thermostaticcircuit cont-rolling devices, the thermostat blade carries the currentfor the operating electromagnet of a contactor or other electricalcircuit controlling device controlled thereby. This may result inheating the thermostat blade sufliciently to introduce inaccuracies inthe temperature control. Also due to the facts that the electromagnetcircuit may be of an inductive nature and that the thermostat blademoves slowly when the thermostat opens its contacts, sparking ordinarilyresults with attendant deterioration of the contacts of the thermostat.It is, therefore, desirable that the current carrying and interruptingduties oii) the thermostat be reduced as far as possf 1e.

Hence, it is the principal object of my in vention to provide anelectromagnetic relay control which in service of the above characterrequires the thermostat to handle a minimum amount of energy to obtainreliable operation of a contactor and in this way reduces sparking atthe contacts and 33 insures longer life of the thermostat.

Other ObJGCtS will appear hereinafter.

In the preferred embodiment of my invention I provide a contactor whichis biased to the open position and is operated by means 5 of anelectromagnet. This electromagnet is provided with a winding designed tobe normally energized from an alternating current source sufficientlyonly to maintain the contactor in closed position but not sufficientlyto close the contactor. A means either in the form of a second windingmounted upon the electromagnet or connected in series with the windingon the electromagnet is provide-d for furnishing additional magneticflux either substantially in phase or in opposite phase with the flux ofthe normally energized Winding for causing operation of the contactor toand from the closed position. For this purpose a transformer having itsprimary con- 5 'nected to the source normally energizing theelectromagnet has a mid-tap provided in its secondary or low voltagecircuit and a thermostat for controlling the energization of the secondwinding from the opposite halves of the secondary circuit so as toincrease or decrease the total magnetization 'of the electromagnet bycausing a current to flow through this second winding eithersubstantially in phase or in opposite phase with the current flowingthrough the winding which is normally energized only sufiiciently tomaintain the contactor in closed position. The increase in themagnetization of the electromagnet will be sufficient to cause thecontactor to close and conversely the decrease in the magnetization ofthe electromagnet will result in the opening of 'the contactor which isnormally biased to the open position.

The transformer secondary as pointed out above is provided .with amid-tap and the thermostat with a blade movable between a. pair ofcontacts, one of said contacts being connected to each side of thesecondary of the transformer. In the one form of my invention the secondwinding on the e1ectromagnet is connected to the thermostat blade and tothe mid-tap of the secondary of the transformer. The thermostat whenmoving 8 from one to the other of its contacts causes reversal of thephase of the current flowing through the second winding. In the otherform of my invention, in which I make use of a second transformer, theprimary of the second transformer is connected to the thermostat bladeand to the mid-tap of the secondary of the first transformer. Thesecondary of the second transformer is connected in series with the coilof the electromagnet. A reversal of the phase of the applied voltage tothe primary of the second trans former results in a reversal of thevoltage in the secondary thereof which is either in phase or out ofphase with the applied voltage on 5 the coil of the electromagnet, thusincreasing the magnetization or decreasing the magnetization of theelectromagnet to close or open the contactor thereof.

A better understanding of my invention 10o may be had by reference tothe drawing and the detailed description given below.

In the drawing, Fig. 1 represents a preferred embodiment of myinvention. Fig. 2 shows a modification thereof.

In Fig. 1 an electromagnet comprising a core 11 and the windings 10 and12 actuates the contactor 13 to open and close its contacts. Thecontactor 13 is biased to the open position by meansof a spring 14. Thewinding 10 is energized directly and continuously from the lines L and Lbut only sufliciently to maintain the contactor 13 in its closedposition. Connected to the same source of supply as the winding 10 isthe transformer 15 which is provided on its low voltage or secondaryside with a mid-tap 16. Each side of the transformer is connected to oneof the contacts 18 and 19 of the thermostat which is provided with themovable blade 17. The mid-tap of the secondary of the transformer andthe blade of the thermostat are connected to opposite sides of thewinding 12 mounted upon the same core as the winding 10.

In the operation of the device when the thermostat blade closesupon thecontact 18, for example, the current through the winding 12 will be inphase with the current through the winding 10. The transformer actionbetween the windings 12 and 10 will result in an increase in the fluxpassing'through the electromagnet which will in turn increase the pullexcited thereby to close the contactor 13. When the thermostat blade 17moves to a central position between the two contacts 18 and 19 due tothe fact that the winding 10 is continuously energized sufficiently tomaintain the contactor 13 closed the contactor will remain in the closedposition. Whenthe thermostat blade 17 closes upon the contact 19 it willbe observed that the winding 12 is energized from the other half of thetransformer 15 with the result that the current flowing through thewinding 12 is opposite in phase with the current flowing through thewinding 10. The transformer action between the windings 12 and 10results in a decrease in the flux of the electromagnet to such an extentthat the bias of the contactor 13 is suflicient to open the contactor.It is, of course, understood that proper values. of inductance andresistance must be selected for the windings 10 and 12 to result inproper operation of the device.

In Fig. 2 the electromagnet is provided with only one winding 20 whichis continuously energized from the supply lines L and L ,The contactor21is biased to the open position by means of the spring 22. A trans- 00former 24 is energized from the lines L and L and has provided on itssecondary winding a mid-tap 25. A thermostat is provided with the blade26 movable between the con tacts 27 and 28 one of said contacts beingconnected to 'eachside of the transformer.

A second transformer 23 is provided having its primary connected to thethermostat blade and to the mid tap of the secondary of the firsttransformer and its secondary side is connected in series with thewinding 20 of the electromagnet.

In operation the winding 20 is continuous- 1y energized from the lines Land L ccntly to maintain the contactor in its closed position when onceit has been closed. \Vhen the thermostat blade 26 moves to close thecontact 27 thereof, for example, the transformer 23 becomes energized sothat its secondary voltage assists the applied voltage to increase theexciting current to the winding 20 which results in the closing of thecontac: tor. \Vhen the transformer 23 is deenergized the current flowingthrough the winding 20 will be sufficient to maintain the contactorclosed. It is, of course, understood that the reactance of the secondaryof the transformer 23 is such that sufiicient current will be permittedthrough the winding 20 to maintain the contactor closed. VVh'cn thethermostat 26 closes on the contactor 28 the voltage of the secondary ofthe transformer 23 will be reversed in phase with respect to the appliedvoltage thereby bucking this voltage and decreasing the energization ofthe winding 20 to such an extent as to permit the bias on the contactorto open the same.

It will thus be seen that by my invention I avoid passing heavy currentsthrough the thermostat proper and thereby eliminate the objectionspointed out above.

The embodiment of the invention illustrated and described herein hasbeen selected for the purpose of clearly setting forth the principlesinvolved. It will be apparent. however, that the invention issusceptible of suiiibeing modified to meet the dflerent conditionsencountered in its use, and I, therefore, aim to cover by the appendedclaims all of the modifications within the true spirit and scope of myinvention.

What I claim as new and desired to secure by Letters Patent of theUnited States, is,-

1. A relay control including a movable magnetic member biased to oneposition, electromagnetic operating means therefor having Cit , rentsource to 2. A relay including a switch member biased to one position,an electromagnet for operating said switch member to another position,energizing windings mounted upon said magnet and connected to beenergized from an alternating current source, one of said windings beingnormally energized to set up a normal alternating flux su'fliclent onlyto maintain the said switch member in said other position when operatedthereto, an-

other winding for providing additional flux substantially in phase withsaid normal flux to operate said switch member to said other positionand substantially in opposite phase with said normal flux to eflect thereturn of the switch member to said one position in accordance with itsbias, and thermostatic means for selectively controlling the winding forproducing the additional flux.

3. A relay for use with an alternating current circuit including aswitch member biased to one position, an electroresponsive devicecontinuously energized from an alternating current source suflicientlyonly to produce a flux to hold said switch member in another position, asecond electroresponsive device positioned to cooperate magneticallywith said first electro-responsive device and adapted to be energizedfrom said alternating current source, and means for selectivelyreversing the energization of said second electroresponsive device fromsaid alternating-curproduce a flux substantially in phase with the fluxin said first electroresponsive device, for increasing the densitythereof to move said switch member to said other po sition, and toproduce a flux substantially in opposite phase with the flux in saidfirst electroresponsive device for decreasing the density thereof toeffect the return of said switch member to biased position.

4. A thermostatic relay for use with an alternating current circuitincluding a switch member biased to one position, an electroresponsivedevice continuously energized from a source of alternating currentenergy sufficiently only to produce a flux to hold said switch member inanother position when operated thereto, a transformer energized fromsaid source of energy, means in the secondary circuit of saidtransformer for reversing the phase of the voltage resulting from saidsecondary and an electroresponsive means cooperating with saidtransformer and said electroresponsive device whereby the flux throughsaid electroresponsive device can be varied to increase or decrease thedensity thereof upon reversal of the voltage phase of said secondary formoving said switch mem- C3 ber between said one and other positions.

5. A thermostatic relay including a switch member biased to oneposition, an electromagnet for moving said member provided with aplurality of windings, one of said windings being continuously energizedfrom a source of alternating current energy only sufliciently tomaintain said switch member in one position and means for energizinganother of sald windings from said source of energy substantially inphase with said one winding to increase the energization of saidelectromagnet to move said switch member to another position or forenergizing said other winding from said source of energy substantiallyin opposite phase with said one winding to decrease the energization ofsaid electromagnet to permit said switch member to move to its otherposition, and a thermostatic means controlling said energizing means tocause said switch member to move between said one position and saidother position.

6. A thermostatic relay including a circuit controlling device biased toone position, an electromagnet for controlling operation of said circuitcontrolling device to another position, windings on said electromagnet,one of said windings being continuously energized from a source ofalternating current energy sufiiciently only to maintain said circuitcontrolling device in said other position when operated thereto, atransformer connected to said source of energy and provided with amiddle tap in its secondary winding, a thermostat provided with amovable blade and a pair of contacts, one secondary terminal of saidtransformer being connected to one of said contacts and the othersecondary terminal of said transformer being connected to another ofsaid contacts, another of said windings being connected to said middletap and said thermostat blade whereby when said blade is on one contactsaid other winding will assist said one winding to close said circuitcontrolling member and when said blade is on the other contact saidother winding will oppose said one winding to open said circuitcontrolling member.

7. A thermostatic relay including a circuit controlling member biased toan open position, an electromagnet continuously energized from a sourceof alternating current energy to set up a normal alternating fluxsufficient only to maintain said circuit controlling member in closedposition when operated thereto, means energized from said source ofenergy for providing additional flux substantially increase themagnetization of said electromagnet to close said circuit controllingmember or substantially in opposite phase with said normal flux todecrease the magnetization of said electromagnet to open said circuitcontrolling member, and a thermostatic means for selectively controllingsaid additional flux providing means.

8. A thermostatic relay including a switch member biased to openposition, an electromagnet continuously energized from an alternatingcurrent source of energy sufiicient- 1y only to maintain said switchmember in a in phase with said normal flux to.

closed position, a transformer connected to be energized from saidsource of energy, a second transformer connected to affect theenergization of said electromagnet and ther- 5 mostatic means forconnecting said second transformer to said first transformer to beenergized thereby to increase the energization of said electromagnet toclose said switch member or for connecting said second transformer tosaid first transformer to decrease the energization of saidelectromagnet to open said switch member.

9. A thermostatic relayincluding a circuit controlling member biased toan open position, an electromagnet continuously energized from analternating current source of energy sufliciently only to maintain saidcircuit controlling member in closed position, a transformer energizedfrom said source of energy and provided with a mid-tap in its secondarywinding, a thermostat provided with a blade and a pair of contacts, onesecondary terminal of said transformer being connected to one of saidcontacts and the other secondary terminal of the transformer beingconnected to the other contact, a second transformer connected to affectthe energization of said electromagnet, one side of the primary thereofbein connected to said mid-tap and the other side of the primary to saidblade, said blade when on one contact causing said second transformer toincrease the 'energization of said electromagnet to close said circuitcontrolling member and when on the other contact to decrease theenergization of said electromagnet to open said circuit controllingmember. a

In witness whereof, I have hereunto set my hand this 14 day of Aug,1930. CHESTER I. HALL.

